In our New Zealand Patent Specification No. 508895 (also WO 99/67584) there is described a heat exchanger tracking including a spiral heat exchanger with coils and the track between the coils providing a second flow path which improves the efficiency of the heat exchange.
In the design of heat exchangers it is important to ensure that the fluid being heated or cooled stays in the heat exchanger for an optimum time. Another design criteria is to obtain a low pressure drop through the heat exchanger and optimise the heat exchange taking place within the heat exchanger.